Bolt tensioner and wrench



Feb. 28, 1956 M 2,736,219

Filed July 8, 1954 ilnited States Patent BOLT TENSIONER AND WRENCHJoseph May, Parrna Heights, Ohio, assignor to General MotorsCorporation, Detroit, Mich, a corporation of Delaware Application July8, 1954, Serial No. 442,067

Claims. (Cl. 81--52.4)

This invention relates to a tool for tightening bolts or studs and moreparticularly a device for stressing bolts, studs and the like to apredetermined elongation and axial stress.

The present invention has as its principal object to improve thebolt-stressing and nut-tightening device disclosed in United Statespatent application Serial No. 442,068, filed July 8, 1954, in the nameof Morris W. Carlson, entitled Tool, so as to provide a simpler and morefool-proof mechanism in operation.

The device disclosed in the aforementioned application includes meansfor first stressing the stud or bolt axially to predetermined values ofaxial elongating loads and wrench means for subsequently tightening downthe mating nut on the elongated bolt to maintain the axial stress withinthe bolt; a procedure resulting in controlled uniform axial stressing ofthe bolt to achieve an elasticity and flexibility of the bolted jointnot possible with con ventional stud or bolt-tightening methods withouta relatively high percentage of failures during and subsequent to theassembly operation. The aforementioned applica tion further discloses atool including an adaptor member which is adapted to engage the end ofthe bolt beyond its nut. The adaptor carries a power-operated mechanismwhich is selectively energizable to react between the opposite end ofthe bolt or stud through the bolted members to exert a predeterminedelongation and stress on the bolt. An integral gear and socketwrenchprovided in the tool is then utilized to advance the nut on theelongated bolt to take up the slack occurring therein and to bring thenut ino snug relation with the adjacent bolted part.

The above stated object of the present invention is attained byreplacing the integral gear and socket wrench of the aforementionedapplication with a wrench assembly which includes a separate socketwrench member and a separate wrench driving gear member biased axiallyof each other to insure proper engagement of the adaptor member andwrench member with the bolt end and nut, respectively, prior to thebolt-stressing and nut-advancing functions of the device and to preventthe application of excessive torques through the gear member withconsequent undesirable torquing of the bolt or breakage of the gearteeth.

This and other objects of the invention will be more thoroughlyunderstood from the following detailed description in which reference ismade to the accompanying drawing, in which:

Figure 1 is aview of a tool embodying my invention with portions brokenaway and in section.

Figure 2 is an exploded perspective view of certain elements shown inFigure 1.

Referring more particularly to the drawing, Figure 1 illustrates athrough bolt having a necked-down shank portion 10 and a threaded endportion 11 having a nut 24 threaded thereon. The bolt is shown extendedthrough a bore provided in a member 18 which represents one of aplurality of members to be secured together by the nut and 2,736,219Patented Feb. as, 1956 bolt, such as one of two diametrically splitclamping ring halves for securing individual cylinders to an enginecrankcase as disclosed in United States Patent No. 2,674,988. A washermember 22 is shown interposed between the nut 24 and the member 18.

The bolt-stressing and nut-tightening tool, as shown by Figure 1,includes a bolt stressing means comprising an adaptor member 30 providedwith a threaded bore 34 at one end for engaging the threaded end 11 ofthe bolt and with a handwheel 36 secured to the opposite end thereof forturning the adaptor down on the bolt. The bore 34 may be provided with aplug 38 for limiting the threadable engagement of the adaptor memberwith the bolt end. An intermediate shank portion 32 of the adaptor isslidably and rotatably embraced by an annular cylinder 40 which isconnectible to a controllable source of pressure fluid, not shown, by aconduit 44. An annular piston member 42 is reciprocably mounted withinthe cylinder 40 and forms an expansible chamber therewith. The piston isprovided with a sleeve portion 44 and a collar member 46 threadedthereon which serves to transmit the reaction of the piston to the headof the bolt, not shown, through the clamped members when fluid pressureis supplied to the pressure cylinder 40 while the cylinder acts on thethreaded end of the bolt 10 through the adaptor 30 and its handwheel 36to effect a predetermined axially elongating stress on the bolt inaccordance with the pressure of the actuating fluid supplied by thecontrollable source.

The wrench means 43 of my invention, as shown in Figures 1 and 2, isrotatably mounted within the sleeve portion 44 of the piston and isretained therein by the collar 46. The wrench means includes an assemblyin which a wrench socket member 49 and a socket driving gear member 50are formed separately. These two members are provided with telescopingdogs 49 and 50 to form a driving connection therebetween and are springbiased axially of each other by a plurality of springs 48 into abuttingrelation with the piston-carried collar and a pinion gear 52,respectively. The gear 50 meshes with and is driven by the bevel gearpinion 52 which is journalled in and projects laterally from the side ofthe piston member 42 as shown at 54. The gear 52 may be rotated eitherby a manually operable knob 56, as shown, or by a suitable power device,not shown. The springs 48 are seated at one end Within axially extendingbores 49 in the socket member and are seated at their opposite endagainst the geared member 50 which is provided with an internal springguide pin 50" for each spring. By proper selection of the springconstant for each of the springs 48" the socket driving gear 50 willtend to. be shifted axially out of engagement with the pinion 52 whenthe nut has been snugged down the desired amount against the washer 22thereby preventing undesired axial and torsional stressing of the boltby the nut and thereby insuring precision uniformity in the boltstressing. The axial shifting of the driving gear 50 will also occurshould the nut become frozen on the bolt for any reason, such ascross-threading, which might result in breaking of the gear teeth. Itwill thus be seen that this spring-biased drive arrangement serves toprotect the tool and prevents excessive torque application to the wrenchmeans to thereby avoid over-stressing of the bolt 10 whether the pinionis driven by power or manual means.

The spring-biased drive arrangement of the wrench socket also permitsthe bolt adaptor 3%) to be threaded upon the bolt end 11 to the properdepth of engagement without the socket necessarily telescopicallyembracing the nut 24. With the wrench means of this invention, if thesocket 49 has not embraced the nut 24, after the threaded adaptor hasproperly engaged the bolt end and either before or after elongating thebolt .10, .the pinion 52 can be rotated slowly until the socket is insuch a position' thatthe springs 48" will urge it axially totelescopically embrace the nut. With integral socket and gear, disclosedin the aforementioned patent application, it necessaryfto utilizemechanical references to insure that the"a'd aptor has engaged the boltend to a proper depth b'eforeth'e' cylinder was energized to elongatethe bolt.

"The tool illustrated maybe utilized for threaded members of differentassorted sizes by provision for interchangeableadaptor members 3b andwrench socket members 49. "The adaptor member 30 is axially removablefrom the tool'by removing the nut 58 and radial or axial pins, notshown, non-rotatably securing the handwheel 36 on the external end ofthe adaptor. Either the entire wrench assembly 48' or merely the wrenchsocket 49 are removable "frorn the tool by first removing the retainingcollar 46. It will be apparent that the adaptor and socket member can bereplaced with similar members of the desired size by reverse procedures'invention contemplates an improved device for tightening nut and-boltmembers by a method which basically comprises the steps of firstelongating the bolt member with a predetermined axial stress, andsecondly advancing the nut member upon the elongated bolt into snugrelationship with the adjacent one of a plurality of bolted-togethermembers to maintain the predetermined elongating stress within the bolt.Other secondary steps will become apparent, however, from the detaileddiscussion below of the operation and use of the aforedescribednut-and-bolt tightening tool embodying the improved wrench means of myinvention.

' The bolt nut may be advanced upon the bolt by either conventionalmeans before using the tool of this invention for tightening purposes orby the socket wrench provided in the tool. If the tool is to be used asan assembly wrench, the nut will be placed within the socket 4-9 beforeturning on the bolt. If the nut is already threaded on the bolt, theside knob 56 is used to help slip the socket upon the nut. In eithercase, once the nut has been initially turned down on'the bolt, theadaptor is pushed into engagement with the bolt and is then threadablyadvanced upon the bolt by rotation until it engages the threaded boltend to a proper depth as controlled by the plug 38 or similar stop meansdetermined by external or mechanical reference. The expansible chamberformed by the cylinder 4b and the piston 42 is then connected to thecontrolled fluid pressure source through the fluid pressure line 41 toproduce a predetermined hydraulic load axially stressing and elongatingthe bolt. The socket 49 is then rotatably driven by the gears 50 and 52advancing the nut toward the head end of the bolt and into snug relationthe washer 22 without appreciable application of torque to the bolt. Inthis manner the looseness resulting from the elongation of the bolt isremoved and the nut n its advanced position maintains the predeterminedaxial stress upon the elongated bolt when the fluid pressure is relievedand the tool is removed.

It should be noted that the bolt or stud tightener of my nvention can beutilized both as an assembly and tightenmg wrench and that it is notnecessary to the practice of my invention that the stressing of the boltmembers be accomplished during'assembly. It will be appreciated thatthere are numerous articles of manufacture, such as engmes or the likein which it would be advantageous to precis on tighten all of the boltsonly after final assembly.

While the foregoing description and figures have been confined to onespecific embodiment of the invention, it

will be apparent to those skilled in the art that numerous modificationscan be made Without departing from the SplIlt'flHd scope of theinventive concepts thereof. Accordm gly, it is to be understood that theforegoing ar to be interpreted as illustrative only and not in alimiting sense, reference being had to the appended claims to determinethe scope ofv the invention. 7 I

I claim:

'lr'A'nut-and-bolt tightening device comprising a cylinder having meansassociated therewith for engaging the free end of a bolt above its nut,a piston reciprocably mounted within said cylinder and having one endthereof adapted to react against the opposite end of said bolt, meansoperable to supply fluid to said cylinder at a given pressure to causesaid cylinder and said piston to apply a predetermined axial tensilestress to said bolt thereby ating the bolt, and means carried by saidpiston for cing the nut toward the opposite end of the bolt while thetensile stress is maintained, said last mentioned means including aspring-biased axially shiftable socket wrench for said nut.

2. A nut-and-bolt tightening device comprising a hydraulic cylinderhaving means associated therewith for engaging the free end of a boltabove its nut and a plurality of members secured thereby, a pistonreciprocably mounted within said cylinder and having one end thereofoperable to react against the adjacent one of the members, said cylinderbeing connectible to a source of hydraulic pressure adapted to supplyhydraulic fluid of a given pressure to said cylinder to produce apredetermined axial stress elongating the bolt, and means carried bysaid piston for advancing the nut into snug relation with the adjacentmember to maintain the stress when the device is de-energized andremoved, said last mentioned means including a wrench socket member, asocket driving member, and a spring biased telescopic driving connectionbetween said socket member and said driving member.

3. A device for tightening a nut and a bolt securing a plurality ofmembers together comprising means for applying a predetermined axialstress to the bolt to effect an elongation thereof prior to tighteningthe nut thereon and means associated with said first means for advancingthe nut into snug relation with the adjacent one of the plurality of'members to maintain the elongation of said bolt after'the'removal of'thedevice, said last mentioned means including a spring-biased axiallyshiftable socket wrench for said nut and a gear member having atelescoping driving connection with said socket'wrench.

4. A device'for applying a predetermined axial stress to a bolt securinga plurality of members together prior to tightening a nut thereoncomprising an adaptor for engaging the bolt 'e'nd above the "nutinitially placed thereon, a'hydraulic cylinder carried by said adaptorhaving a piston reciprocably mounted therein, one end of said pistonbeingadapted to 'rejactagainst the adjacent member of the plurality ofmembers, said cylinder being connectible to a controllable source ofhydraulic pressure to apply an axial stress tothe bfolt effecting anelongation thereof, a wrench socket rotatably mounted by said piston andadapted to embrace the nut, and a gear member having a spring-biasedtelescoping driving connection with said wrench socket and beingengageable with geared driving means whereby the nut may be advancedinto snug relationship with the adjacent member of said plurality ofmembers to maintain the'stressed elongation of said bolt.

5. A device'for applying a predetermined axial stress to a bolt securinga plurality of members together comprising means for 'elfecting theelongation of the bolt prior to tightening down a nut thereon and meansfor advancing the nut on' theelongated bolt into snug relationship withthe'adjacenfmember of said plurality of members, said second meansincludinga spring-loaded axially shiftable socket Wrench for said nut.

6. A tool comprising means for initially applying an axially elongatingstress to a bolt or stud securing aplurality of members together andmeans for subsequently tightening a nut thereon into snug relation withthe adjacent one of the plurality of members whereby the elongao o the12 sma nt ines u n. emo a of the d v a a t me ioned mean nclud g. a pr n-b d ving connection releasable to, preyent application of torsionalstresses to said bolt. through said. nut.

7. A device for applying a predetermined axial tensile stress to a boltsecuring a plurality of members together prior to tightening down a nutthereon, comprising a threaded adaptor for engaging the bolt end beyondthe nut, a cylinder carried by said adaptor having a piston reciprocablymounted therein and being connectible to a source of fluid pressure, oneend of said piston being adapted to react against the adjacent one ofthe members whereby a given fluid pressure applied to said cylinder willapply axial tensile stress to the bolt to the predetermined amount, andwrench means rotatably carried by said piston for tightening the nutinto snug relation with the adjacent member, said wrench means includingan axially shiftable wrench socket, a first gear member having aspring-biased telescopic driving connection with said Wrench socket, anda second gear member drivingly engaging said first gear, saidspring-biased telescopic connection permitting axial shifting of thefirst gear out of driving engagement with said second gear uponapplication of a predetermined torque to said nut.

8. A tool including power means for first applying axial tensilestresses to a bolt and means for then advancing a nut thereon whilemaintaining said axial tensile stresses in said bolt, said lastmentioned means including a driving connection releasable uponapplication of a predetermined torque to said nut.

9. In a wrench for tightening down a nut on a bolt to secure a pluralityof members together, the combination comprising a housing member havinga bore therein, a first gear member journaled in said bore, a secondgear member rotatably mounted by said housing member 6 E adapted todrivingly engage said first gear, and a Wrench socket mounted withinsaid housing bore and having a spring biased telescopic drivingconnection with said first gear member, said spring biased telescopicconnection permitting axial shifting of the first gear out of drivingengagement with said second gear upon application of a predeterminedtorque to said nut.

10. A Wrench assembly for tightening a nut upon a bolt to secure aplurality of members together, comprising, in combination, a wrenchsocket, a gear member hav' ing a spring biased telescopic drivingconnection with said Wrench socket, geared driving means adapted todrivingly engage said first-mentioned gear, and a casing rotatablymounting said wrench socket and said firstmentioned gear, said casingand said gear driving means restraining the axial shifting of saidwrench socket and said gear member in opposite directions, said springbiased telescoping driving connection permitting axial shifting of saidWrench socket toward said first gear and said spring biased telescopingdriving connection permitting axial shifting of the gear member towardsaid socket member and out of driving engagement with said geareddriving means upon application of a predetermined torque to said nut.

References Cited in the file of this patent UNITED STATES PATENTS1,353,600 McBride Sept. 21, 1920 1,389,154 Newhouse Aug. 30, 19212,544,522 Bertelsen Mar. 6, 1951 2,631,485 Stuart et a1. Mar. 17, 1953

